More than 2,000 tourists were cleared from the Eiffel Tower and surrounding areas last night after a series of bomb threats. One of the French capital's largest metro interchanges, at Saint-Michel near Notre Dame cathedral, was also cleared after a warning call to authorities.

The station was re-opened after an hour but the tower was closed for more than three hours while a large police presence kept tourists and onlookers at bay. The all-clear was finally given just before midnight.

A senior French security official had warned earlier this week that the terrorist threat to France was regarded as acute. A law to ban the burka, or full-length veil, in public places passed its final legislative stage when it was approved by the upper house of the French parliament, the Senate, earlier yesterday.

The Eiffel Tower is the most popular monument in France, attracting more than 6,600,000 visitors a year. "The company which runs the tower received an anonymous call at 8.20pm," a police spokesman said. "Special teams including sniffer dogs [are searching] the tower floor by floor." Despite the all clear, scores of police officers and a dozen police vehicles still surrounded the iconic building late last night.

The Saint-Michel station, also searched by police last night, was the scene of a terrorist attack on 25 July, 1995, when a gas bottle exploded killing eight people and injuring 80 others. The attack was carried out by an Algerian islamist terrorist group.

The burqa ban, which would make France the first European country to outlaw the full veil, is due to take effect next spring but is likely to be overturned in its present form by France's constitutional watchdog, the Conseil constitutionnel. Offenders would be fined €150 or required to take part in a citizenship class.

Before the vote, Justice Minister Michele Alliot-Marie said the ban had nothing to do with religion. It reaffirmed the French values of equality and dignity of all individuals and would prevent women from simply becoming faceless members of a larger ethnic community.